A damping device has a liquid vessel into which the liquid is injected having the flattening wave motion water surface formed in such a manner that the wave motion direction of the wave motion water surface is a strecher one, damping members are provided in order to damp the sloshing of liquid in the liquid vessel, and wave dissipation devices are disposed at the portion which isn't always soaked in liquid in the liquid vessel. Accordingly, the vibration in a construction occurring by wind, earthquake and the like is absorbed by means of viscosity resistance occurring between liquid and damping member, and the vibration is restricted. Moreover, damping performance can be efficiently exercised by providing various kinds of installation forms.